Showing posts with label toxicology. Show all posts
Showing posts with label toxicology. Show all posts

13 June 2021

Dr. Josh Trebach and his Tox Murder Mysteries


I usually interview people and write articles, but not today.

First, let me introduce you to Dr. Josh Trebach, an emergency physician and toxicology fellow at NYC. You can follow him @jtrebach on twitter and following him is a treat for anyone interested in the lovely combination of medicine and mystery.

Second, let me explain why I didn’t interview Dr. Trebach. He writes murder mystery threads. They are so perfectly written, that I asked him for permission to put them, largely unedited, in an article.

So, here’s how he introduces his mysteries: Buckle up - it’s tox murder mystery thread.

Without further ado, here are two of his mysteries. 

Tox murder mystery #1.

A 45 year old man is found dead in the orthopedic room of an emergency department. He has no signs of trauma and no past medical history.

What do you think happened?

Clues

  1. The man was hired by the hospital to clean drain pipes blocked by plaster washed down the sink by silly residents. (Stop washing your plaster down the sink! I see you!! STOP DOING IT! It's nasty and gross)
  2. The material used to make the splints was Plaster of Paris. This product is still used today.
  3. The man was using sulfuric acid to clean the drain and dissolve the clogged up Plaster of Paris. I'm a toxicology fellow, not a drain declogging expert, what do you want from me? I don't know why they used that.
  4. What happens to Plaster of Paris when its gunked up in the pipes?  It gets chewed up by bacteria. Under anaerobic conditions, the bacteria can make a nasty, thick (thicc?) calcium sulfide sludge.
  5. Sulfuric acid + Calcium Sulfide = ??? UGHHHHH chemistry.

Yet, the answer is in here. These two combine in the following chemical reaction, giving us our answer.

  CaS + H2SO4 → CaSO4 + H2S  

The culprit: Hydrogen Sulfide gas was formed by the chemical reaction above and it caused the man to die pretty quickly. Perhaps the only thing abnormal on the patient's skin exam was his silver wedding ring that had tarnished after reacting with the gas.

Hydrogen sulfide is a colorless gas that classically smells like rotten eggs . It gets inhaled into the body and interferes with oxidative phosphorylation and causes cellular hypoxia. What does this translate into? Rapid unconsciousness and cardiopulmonary arrest.

Hydrogen sulfide is scary. People will die in groups because whenever someone (not wearing PPE) goes to rescue the victim, they become exposed to the gas and then pass out/die… and the cycle continues.In fact, at ~1000ppm, breathing will STOP after just 1-2 breaths.

Treatment: Moving the victim to fresh air and giving oxygen, in addition to good supportive care and respiratory/ventilatory support, is key. Antidotes such as sodium nitrite work by inducing methemoglobinemia which scavenges the hydrogen sulfide.

Tox murder mystery #2.

A 33 year old woman is found dead in a bank vault. She has no signs of trauma and no past medical history.

What do you think happened?

Clues

  1. The woman was a bank employee doing normal bank employee things. Unfortunately, when she went into the bank vault, it locked behind her. Whoopsies.
  2. She waved at the camera. She banged on the doors. She pulled the fire alarm (but nothing happened?). She tried her phone but had no service and couldn't even tweet. Imagine the horror.
  3. She figured she would wait an hour or so until someone else opened the vault… yet, over the course of 30 minutes, the woman slowly dropped to the ground and suffocated to death. What happened? Why did she die so quickly? Let’s learn about asphyxiants!
  4. Asphyxiants cause harm by suffocation. There are two categories of asphyxiants– chemical and simple. Chemical asphyxiants (like hydrogen sulfide) interrupt the body's ability to deliver or utilize oxygen.
  5. Simple asphyxiants displace the oxygen in the air, making it so there's less oxygen around for you and your body. Thus, when you take a deep breath, you get a mouthful of NOT OXYGEN. Your body/mitochondria are like "ew seriously?"… and then you suffocate.
  6. But what does any of this have to do with our case? Well, ask yourself--why is there a fire alarm in a bank vault? Most times when you pull a fire alarm, you trigger a water sprinkler system...but then that would cause the money to get nasty and wet. Gross.
  7. So the fire alarm doesn't trigger the release of water. But how else can you put out a fire? By using a CARBON DIOXIDE-BASED FIRE EXTINGUISHER SYSTEM! By releasing carbon dioxide and displacing the oxygen, the combustion reaction cannot occur and fire is put out!

Unfortunately, this woman sealed her fate the moment the fire alarm was pulled. Carbon dioxide filled the bank vault and she suffocated from this simple asphyxiant. Education about the risks with these extinguishers is key– these are preventable deaths.

Simple asphyxiants are everywhere. Virtually every gas (except oxygen) can act as a simple asphyxiant– the dose makes the poison. There are even cases of people dying after being in a room with a bunch of dry ice (sublimation reaction leads to lots of carbon dioxide).

Treatment: Get away from the simple asphyxiant. Get to oxygen. This seems remarkably simple, but unfortunately, can be very challenging in some situations (like when you are trapped in a bank vault).